Water stable fibers and articles comprising starch, and methods of making the same

ABSTRACT

Water stable fibers and articles made therefrom are formed from a thermoplastic composition comprising destructured starch, polyhydric alcohol, triglyceride, and optionally acid. Processes for making water stable compositions may comprise melt extruding a mixture of destructured starch, polyhydric alcohol, triglyceride, and optionally acid, to form an extrudate, and heating the mixture, extrudate, or both to provide a water stable article.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/725,424, filed 11 Oct. 2005.

FIELD OF THE INVENTION

The present invention relates to fibers made from thermoplastic starchcompositions, and articles made therefrom. The fibers and articles arewater stable, or may be rendered so. The invention also relates tomethods of making the fibers and articles.

BACKGROUND OF THE INVENTION

There have been many attempts to make starch-containing fibers,particularly on a high speed industrial level. However, starch fiberscan be much more difficult to produce than films, blow-molded articles,and injection-molded articles containing starch because the material andprocessing characteristics for fibers are much more stringent. Forexample, local strain rates and shear rates can be much greater in fiberproduction than in other processes. Additionally, a homogeneouscomposition may be required for fiber spinning. For spinning finefibers, small defects, slight inconsistencies, or non-homogeneity in themelt are typically not acceptable for current, commercially viableprocesses.

In recent years, attempts have been made to process starch on standardequipment and using existing technology known in the plastic industry.Fibers comprising starch may be desired over conventional plastics for avariety of reasons. Unpredictable fluctuations in price and availabilityof petroleum and its derivatives have created serious disruptions to thestable supply of petroleum-based polymers used in making syntheticfibers, for example, those based on polyolefins. Starch also hasmaterial properties not typically provided by conventional polyolefinplastics, including higher hydrophilicity (such as for improvedabsorbency), as well as affinity and compatibility with other materialsnot normally compatible with polyolefins. Starch may, in some forms,also provide consumer-related benefits, like easy disposability and/orflushability, and/or socially and environmentally relevant properties,like bio-sourcing and biodegradability. Starch may also provide alow-cost alternative to conventional petroleum-based materials, forexample polypropylene.

In conventional processes, starch is typically combined with one or moreplasticizers or other process aids to render it thermoplastic forprocessing, for example by melt spinning or other melt extrusiontechniques. Unfortunately, thermoplastic starch (TPS) is highlysusceptible to moisture. In fact, fibers made of TPS can spontaneouslypick up atmospheric moisture and become tacky. When placed in water, TPSfibers from conventional starch blends partially or fully disintegratewithin hours. Although methods exist for rendering thermoplasticcompositions containing starch more water stable including, but notlimited the addition of petroleum based polymers, there remains an unmetneed for greater water stability in such compositions and in articlesmade from such compositions.

SUMMARY OF THE INVENTION

In some embodiments, the present invention relates to water stablefibers which are made from thermoplastic polymer compositions comprisingdestructured starch, and transesterification reaction products formedfrom a reaction mixture comprising polyhydric alcohol and triglyceride.In some embodiments, the water stable fibers are made from thermoplasticpolymer compositions additionally comprising ester condensation reactionproducts of polyhydric alcohol and acid.

In some embodiments, the invention is directed to a method of makingwater stable fibers. The method comprises the following series of stepswhich may be completed in any suitable order. In one step, a mixture ofdestructured starch, polyhydric alcohol, triglyceride, and acid, isformed. In a further step, the mixture is extruded through a spinneretat an elevated temperature to form fibers. In yet a further step, atransesterification reaction is induced between polyhydric alcohol andtriglyceride, and optionally, an ester condensation reaction is inducedbetween polyhydric alcohol and acid.

In some embodiments, articles are made from the fibers of the presentinvention. Non-limiting examples of articles in include nonwovens.Specific embodiments include personal hygiene articles, absorbentarticles, and packaging.

In general, the present invention provides starch-based compositions,fibers and articles in other forms with improved water stability, andcompositions and processes for making such water stable compositions andarticles. Water stability may be achieved without requiring the use ofpetroleum based polymers including, but not limited to, polyolefins.Water stability can provide a variety of consumer-related benefits. Thefibers, compositions and processes may provide a low-cost alternative toconventional petroleum-based materials. These and additional advantageswill be more apparent in view of the following detailed description.

DETAILED DESCRIPTION

All percentages, ratios and proportions used herein are by weightpercent of the composition, unless otherwise specified. All averagevalues are calculated “by weight” of the composition or componentsthereof, unless otherwise expressly indicated. “Average molecularweight,” or “molecular weight” for polymers, unless otherwise indicated,refers to weight average molecular weight. Weight average molecularweight, unless otherwise specified, is determined by gel permeationchromatography.

“Copolymer” as used herein is meant to encompass copolymers,terpolymers, and other multiple-monomer polymers.

“Reactant” as used herein refers to a chemical substance that is presentat the start of a chemical reaction.

“Mixture” as used herein refers to a mixture of two or more of any of adefined group of components, unless otherwise specified.

“Biodegradable” as used herein refers to the ability of a compound toultimately be degraded completely into CH₄, CO₂ and water or biomass bymicroorganisms and/or natural environmental factors.

“Fiber” as used herein includes staple fibers, fibers longer than staplefibers that are not continuous, and continuous fibers, which aresometimes referred to in the art as “substantially continuous filaments”or simply “filaments”. The method in which the fiber is prepared willdetermine if the fiber is a staple fiber or a continuous filament.

“Monocomponent fiber” as used herein, refers to a fiber formed fromusing one or more extruders from only one polymer. This is not meant toexclude fibers formed from one polymer to which small amounts ofadditives have been added. Additives may be added to the polymer for thepurposes of providing the resulting fiber with coloration, antistaticproperties, lubrication, hydrophilicity, and the like.

“Multicomponent fiber” as used herein refers to a fiber formed from twoor more different polymers that are extruded from separate extruders andspun together to form one fiber.

“Bicomponent fibers” are one type of multicomponent fiber, and areformed from two different polymers. Bicomponent fibers may sometimes bereferred to as “conjugate fibers” or “multicomponent fibers”.Bicomponent fibers may be comprised of polymers that are substantiallyconstantly positioned in distinct zones, both across the cross-sectionof the bicomponent fibers and along their length. Non-limiting examplesof such bicomponent fibers include, but are not limited to: sheath/corearrangements, wherein one polymer is surrounded by another; side-by-sidearrangements; segmented pie arrangements; or even “islands-in-the-sea”arrangements. Each of the aforementioned polymer arrangements is knownin the art of multicomponent (including bicomponent) fibers.

Bicomponent fibers can be splittable fibers; such fibers are capable ofbeing split lengthwise before or during processing into multiple fiberswith each of the multiple fibers having a smaller cross-sectionaldimension than that of the original bicomponent fiber. Splittable fibershave been shown to produce softer nonwoven webs due to their reducedcross-sectional dimensions. Representative splittable fibers useful inthe present invention include type T-502 and T-512 16 segment PET/nylon6, 2.5 denier fibers, and type T-522 16 segment PET/PP splittablefibers, all of which are available from Fiber Innovation Technology,Johnson City, Tenn.

“Biconstituent fibers” as used herein, refers to fibers which have beenformed from at least two starting polymers extruded as a blend from thesame extruder. Biconstituent fibers may have the various polymercomponents arranged in relatively constantly positioned distinct zonesacross the cross-sectional area of the fiber and the various polymersare usually not continuous along the entire length of the fiber. In thealternative, biconstituent fibers may comprise a blend, that may behomogeneous or otherwise, of the at least two starting polymers. Forexample, a bicomponent fiber may be formed from starting polymers whichdiffer only in molecular weight.

The polymers comprising biconstituent fibers may form fibrils, which maybegin and end at random along the length of the fiber. Biconstituentfibers may sometimes be referred to as multiconstituent fibers.

The terms “non-round fibers” and “shaped fibers” as used interchangeablyherein, refer to fibers having a cross-section that is not circular, andincludes, but is not limited to those fibers that are “shaped fibers”and “capillary channel fibers.” Such fibers can be solid or hollow, andthey can be tri-lobal, delta-shaped, and are preferably fibers havingcapillary channels on their outer surfaces. The capillary channels canbe of various cross-sectional shapes such as “U-shaped”, “H-shaped”,“C-shaped” and “V-shaped”. One preferred capillary channel fiber isT-401, designated as 4DG fiber available from Fiber InnovationTechnologies, Johnson City, Tenn. T-401 fiber is a polyethyleneterephthalate (PET polyester). Further examples of shaped fibers of usein the present invention are found in U.S. Pat. Pub. No. 2005/0176326A1.

The terms “nonwoven web” or “web” are used interchangeably herein, andrefer to a layer of individual fibers or threads that are interlaid, butnot in an identifiable manner as in a knitted or woven web. Nonwovenwebs may be made via processes known in the art, including those thatcomprise the following non-limiting examples. Fiber laying processes ofuse may include, but are not limited to: carding; airlaying; andwetlaying. Processes comprising filament spinning from resin andintegrated webforming include, but are not limited to: spunbonding;meltblowing; coforming; and forming spunbond-meltblown-spunbondcomposites. Fiber bonding processes of use may include, but are notlimited to: spunlacing (i.e. hydroentanglement); cold calendering; hotcalendering; air thru bonding; chemical bonding; needle punching; andcombinations thereof.

“Compostable” as used herein refers to a material that meets thefollowing three requirements: (1) the material is capable of beingprocessed in a composting facility for solid waste; (2) if so processed,the material will end up in the final compost; and (3) if the compost isused in the soil, the material will ultimately biodegrade in the soil.

“Comprising” as used herein means that various components, ingredientsor steps can be conjointly employed in practicing the present invention.Accordingly, the term “comprising” encompasses the more restrictiveterms “consisting essentially of” and “consisting of”. The presentcompositions can comprise, consist essentially of, or consist of any ofthe required and optional elements disclosed herein.

Markush language as used herein encompasses combinations of theindividual Markush group members, unless otherwise indicated.

All percentages, ratios and proportions used herein are by weightpercent of the composition, unless otherwise specified. All averagevalues are calculated “by weight” of the composition or componentsthereof, unless otherwise expressly indicated.

All numerical ranges disclosed herein, are meant to encompass eachindividual number within the range and to encompass any combination ofthe disclosed upper and lower limits of the ranges.

The present invention is directed to water stable fibers, articlescomprising water stable fibers, and processes for making the same.Within the context of the present specification, “water stable”describes a material that remains intact after two weeks in 200 ml oftap water at room temperature according to the following procedure. 200ml of tap water are charged to a clean glass container, to which about0.5 grams of material is added. The material should be in a form thatdisplays an aspect ratio of greater than about 1:20 with a minimum axisno larger than 1 mm. This condition is easily met for fibers of diameterless than 1 mm. Suitably, at least 10 test pieces should be added to thecontainer with water. The container is closed and agitated by an orbitalmechanical shaker (for example a Madell Technology ZD-9556, Omaha Nebr.)at 100 rpm for 15 minutes to coat the material with water. After 1 hour,24 hours, 48 hours, 72 hours and two weeks, the contents are agitated byan orbital mechanical shaker at 100 rpm for 15 minutes. If, after twoweeks, the material is still intact, with no disintegration, thematerial is considered to be water stable. Suitably, each test pieceremains a single entity with no disintegration. The material may exhibitsome swelling or other dimensional change and still be water stable. Ina specific embodiment, the material does not exhibit a substantialdecrease in dimension when subjected to the described water stabilitytest. The term “substantial decrease in dimension” means that theaverage maximum axis length of the tests pieces exhibits more than a 15%decrease on average. In a more specific embodiment, the average maximumaxis length of the test pieces exhibits no more than a 10% decrease onaverage. Averages are typically based on ten or more test pieces.

The present fibers, articles comprising fibers, and processes employstarch. In one embodiment, the invention is directed to fibers made froma thermoplastic starch composition comprising destructured starch,polyhydric alcohol, and triglyceride and/or acid; the fibers may berendered water stable by heating. The thermoplastic polymer compositionsof the present invention are made from mixtures of materials alsoreferred to herein as “starch compositions”.

Starch

Starch is naturally abundant and can be relatively inexpensive.Thermoplastic starch can have desirable properties not typicallyobserved in conventional petroleum-based polymers including, but notlimited to, biodegradability, compostability, natural hydrophilicity andcompatibility with materials traditionally incompatible withpetroleum-based polymers.

Starch may take several different forms. As used herein, “native starch”means starch as it is found in its naturally occurring, unmodified form.Any suitable source of native starch is of use in the present invention.Non-limiting examples of sources include: corn starch, potato starch,sweet potato starch, wheat starch, sago palm starch, tapioca starch,rice starch, soybean starch, arrow root starch, bracken starch, lotusstarch, cassava starch, waxy maize starch, high amylase corn starch,commercial amylase powder, and combinations thereof.

Native starch generally has a granular structure. In order to renderstarch capable of further processing, it is typically subject to adestructuring process. Without wishing to be bound by theory, it isbelieved that a starch granule is comprised of discrete amylopectin andamylase regions. To convert native starch to “destructured starch”, theregions are broken apart during the destructurization process, which isoften followed by a volume expansion of the starch, particularly in thepresence of additives including, but not limited to, plasticizer. Thepresence of a plasticizer, such as polyhydric alcohol, when starch isdestructured typically increases the starch's viscosity as compared tostarch that is destructured in its absence. The destructuring process istypically irreversible. In some embodiments of the present invention, itmay be desirable to destructure the starch as fully as possible, so asto avoid “lumps” which may have an adverse impact in subsequentprocessing steps including, but not limited to fiber spinning processes.

Native starch of use in the present invention may be destructured priorto its inclusion in the mixtures of present invention. In addition, orin the alternative, native starch may be destructured after it is in themixture, i.e., in situ. In some embodiments of the present invention,the use of native starch is less expensive than using destructuredstarch, as it eliminates the use of a separate, destructuring step.

Native starch may be destructured using any suitable means. At leastpartial destructuring may be achieved through means including, but notlimited to: heating; enzyme modification; chemical modificationincluding but not limited to ethoxylation and the like (such as byadding ethylene oxide for example); chemical degradation; andcombinations thereof. Agents that may act as starch plasticizers may beused to destructure the starch. In some embodiments, these agents mayremain mixed with the starch during further processing. In otherembodiments, the agents may be transient, meaning that they are removedso that they are not present during further processing, and/or in thefinal fiber or article comprising the fiber.

In some embodiments, destructured starch may encompass native starchthat has been destructured by modification, as discussed above. Modifiedstarch is defined as a native starch that has had its native molecularcharacteristics (molecular weight or chemical structure) altered in anyway. For example, in some embodiments, if the molecular weight of thenative starch is changed, but no other changes are made to the nativestarch, then the starch can be referred to as a modified starch.Chemical modifications of starch typically include acid or alkalihydrolysis and oxidative chain scission to reduce molecular weight andmolecular weight distribution. Native starch generally has a very highaverage molecular weight and a broad molecular weight distribution (e.g.native corn starch has an average molecular weight of up to about60,000,000 grams/mole (g/mol)). The average molecular weight of starchcan be reduced as desired for the present invention by acid reduction,oxidation reduction, enzymatic reduction, hydrolysis (acid or alkalinecatalyzed), physical/mechanical degradation (e.g., via thethermomechanical energy input of the processing equipment), andcombinations thereof. The thermomechanical method and the oxidationmethod offer an additional advantage when carried out in situ. The exactchemical nature of the starch and molecular weight reduction method isnot critical as long as the average molecular weight is in an acceptablerange. Ranges of weight average molecular weight for starch or starchblends added to the melt can be from about 3,000 g/mol to about8,000,000 g/mol, from about 10,000 g/mol to about 5,000,000 g/mol, orfrom about 20,000 g/mol to about 3,000,000 g/mol. In other embodiments,the average molecular weight is otherwise within the above ranges butabout 1,000,000 or less, or about 700,000 or less. Starches havingdifferent molecular weights may be mixed as desired for use in theinvention.

In some embodiments, destructured starch encompasses substituted starch.Substituted starches are starches that have some of their alcohol (i.e.,hydroxyl) functional groups replaced by other chemical moieties. Ifsubstituted starch is desired, chemical modifications of starchtypically include etherification and esterification. Chemicalmodification can be accomplished using ethylene oxide, otherwise knownas ethoxylation, resulting in destructured starch as discussed above.Substituted starches may be desired for better compatibility ormiscibility with the thermoplastic polymer and plasticizer. However, itmay be desirable to balance substitution with the reduction in the rateof degradability. The degree of substitution of the chemicallysubstituted starch is typically from about 1% to about 100% (i.e.,completely substituted). Alternatively, a low degree of substitution,from about 1% to about 6%, may be used.

In some embodiments, the starch compositions or the thermoplasticcompositions of the present invention comprise from about 1% to about99%, from about 30% to about 90%, from about 50% to about 85%, or fromabout 55% to 80% of starch, including the bound water content of thestarch. The starch is selected from the group consisting of nativestarch, destructured starch (which may include modified starch and/orsubstituted starch) and combinations thereof. The term “bound water”refers to the water found naturally occurring in starch before it ismixed with other components to make the composition. In contrast, theterm “free water” refers to water that may be added to a composition ofthe present invention. For example, free water may be incorporated as orwith a plasticizer. A person of ordinary skill in the art will recognizethat once the components are mixed in a composition, water can no longerbe distinguished by its origin. Starch that has not been subjected todrying processes typically has bound water content under ambientconditions of about 5% to about 16% by weight of starch. In someembodiments of the present invention, the compositions and articles ofthe invention comprise at least about 50% destructured starch, morespecifically, at least about 60% destructured starch.

Starch of use in the present invention may comprise any combination ofstarches as described generally or specifically herein, or as known inthe art. Suitable starches of use may be selected from the groupconsisting of: cold water insoluble starch; cold water soluble starch;and combinations thereof. Wherein “cold water” refers to water that isat or below 25° C. As used herein, cold water insoluble starch is starchthat dissolves less than 25% in water at 25° C.

Thermoplastic starch used herein refers to a starch composition that iscapable of flowing when at an elevated temperature (significantly abovenormal ambient temperature; generally above 80° C.), to the extent thatthe starch, or a composition comprising the starch, can be adequatelyprocessed, for example, for formation of homogeneous mixtures, spinningperformance and/or desired fiber properties. The fibers and/or plasticarticles comprising them are capable of solidifying after the elevatedtemperature is lowered to ambient temperatures to retain the shapedform.

Polyhydric Alcohol

“Polyhydric alcohol” as used herein refers to an alcohol having two ormore alcohol (i.e., hydroxyl) functional groups. Without wishing to bebound by theory, it is believed (as mentioned above) that polyhydricalcohol may act as a starch plasticizer in the starch compositions ofthe present invention. In other words, polyhydric alcohol is believed toenable the starch to flow and to be processed, i.e., to create athermoplastic starch.

Any suitable polyhydric alcohol or combination of polyhydric alcohols isof use. Non-limiting examples of suitable polyhydric alcohols include:glycerol (also known in the art as glycerin), glycol, sugar, sugaralcohol, and combinations thereof. Non-limiting examples of glycols ofuse include: ethylene glycol, propylene glycol, dipropylene glycol,butylene glycol, hexane triol, and the like, polymers thereof, andcombinations thereof. Non-limiting examples of sugars of use include:glucose, sucrose, fructose, raffinose, maltodextrose, galactose, xylose,maltose, lactose, mannose, erythrose, pentaerythritol, and mixturesthereof. Non-limiting examples of sugar alcohols of use include:erythritol, xylitol, malitol, mannitol, sorbitol, and mixtures thereof.In specific embodiments of the present invention, the polyhydric alcoholcomprises glycerol, mannitol, sorbitol, and combinations thereof.

In general, the polyhydric alcohol is substantially compatible with thepolymeric components with which it is intermixed. As used herein, theterm “substantially compatible” means that when heated to a temperatureabove the softening and/or the melting temperature of the composition,the polyhydric alcohol is capable of forming a visually homogeneousmixture with polymer present in the component in which it is intermixed.In some embodiments, the plasticizer is water soluble.

In some embodiments of the present invention, the polyhydric alcohol mayalso be used as a destructuring agent for starch. In these embodiments,upon destructuring the starch, the polyhydric alcohol may act as aplasticizer to the destructured starch, thereby rendering itthermoplastic. In further embodiments, upon destructuring the starch,the polyhydric alcohol may be removed and substituted with a differentplasticizer to render the destructured starch thermoplastic. In someembodiments, the polyhydric alcohol may improve the flexibility of theresulting fibers and/or plastic articles comprising them.

Polyhydric alcohol is included in the present thermoplastic compositionsin any suitable amount for either destructuring starch and/or renderingdestructured starch thermoplastic. Generally, the amount of polyhydricalcohol needed is dependent upon the molecular weight of the starch, theamount of starch in the mixture, the affinity of the polyhydric alcoholfor the starch, and combinations thereof. The polyhydric alcohol shouldsufficiently render the starch component thermoplastic so that it can beprocessed effectively, for example to form plastic articles. Generally,the amount of polyhydric alcohol increases with increasing molecularweight of starch. Typically, the polyhydric alcohol can be present incompositions of the present invention in an amount of from about 2% toabout 70%, from about 5% to about 50%, from about 10% to 30%, or fromabout 15% to about 25%.

Acid

Acids of use in the present invention have at least one functional groupselected from the group consisting of: carboxylic acid, carboxylic acidanhydride, and combinations thereof. Such acids include, but are notlimited to, monoacids, diacids, polyacids (acids having at least threeacid groups), polymers comprising at least one acid moiety, co-polymerscomprising at least one acid moiety, anhydrides thereof, and mixturesthereof.

Non-limiting examples of acids of use include: adipic acid, sebaticacid, lauric acid, stearic acid, myristic acid, palmitic acid, oleicacid, linoleic acid, sebacic acid, citric acid, oxalic acid, malonicacid, succinic acid, glutaric acid, maleic acid, fumaric acid, phthalicacid, isophthalic acid, terphthalic acid, acrylic acid, methacrylicacid, itaconic acid, glycidyl methacrylate, and combinations thereof.Anhydrides of such acids may also be employed within the context of thepresent invention. Non-limiting examples of acid anhydrides of useinclude: maleic anhydride, phthalic anhydride, succinic anhydride andcombinations thereof.

Polymers and co-polymers comprising at least one acid moiety, and/ortheir anhydrides are of use. Suitable polymers and copolymers include,but are not limited to, those comprising monomer units of acrylic acid,methacrylic acid, itaconic acid, glycidyl methacrylate, anhydridesthereof, and combinations thereof. The polymer can contain other monomerunits in conjunction with these acid monomer units. For example,ethylene-acid monomer copolymers such as ethylene-acrylic acid copolymercan be used. In a specific embodiment, the copolymers comprise at least50 mol % of acid monomer units. The molecular weight of such polymersand copolymers can vary from as low as about 2,000 to over about1,000,000. An example of a suitable polyacrylic acid is from AldrichChemical Company, having a molecular weight of about 450,000. An exampleof a suitable ethylene-acrylic acid copolymer is Primacore 59801 fromDow Chemical, having an acrylic acid content of at least 50 mol %.

In specific embodiments, the acid comprises at least one diacid,polyacid, acid polymer or copolymer, or a mixture thereof. In otherembodiments, the acid comprises a diacid, alone or in combination withanother acid, for example a monoacid. In further embodiments, the acidcomprises adipic acid, stearic acid, lauric acid, citric acid,polyacrylic acid and/or ethylene-acrylic acid copolymer.

Typically, the acid is employed in the starch composition in an amountof from about 0.1% to about 30%, from about 1% to about 20%, or fromabout 2% to about 12%. In some embodiments, the molar ratio of alcoholfunctional groups to acidic functional groups in the starch compositionis at least about 1:1, or at least about 4:1. In some embodiments, themolar ratio of alcohol functional groups to acidic groups in the starchcomposition is from about 1:1 to about 200:1, or from about 1:1 to about50:1.

Triglyceride

Any suitable triglycerides, which are also known in the art astriacylglycerols, are of use in the present invention. Non-limitingexamples of triglycerides of use include: tristearin, triolein,tripalmitin, 1,2-dipalmitoolein, 1,3-dipalmitoolein,1-palmito-3-stearo-2-olein, 1-palmito-2-stearo-3-olein,2-palmito-1-stearo-3-olein, trilinolein, 1,2-dipalmitolinolein,1-palmito-dilinolein, 1-stearo-dilinolein, 1,2-diacetopalmitin,1,2-distearo-olein, 1,3-distearo-olein, trimyristin, trilaurin andcombinations thereof.

Suitable triglycerides may be added to the present compositions in neatform. Additionally, or alternatively, oils and/or processed oilscontaining suitable triglycerides may be added to the compositions.Non-limiting examples of oils include coconut oil, corn germ oil, oliveoil, palm seed oil, cottonseed oil, palm oil, rapeseed oil, sunfloweroil, whale oil, soybean oil, peanut oil, linseed oil, tall oil, andcombinations thereof.

Typically, triglycerides are employed in the starch compositions in anamount of from about 0.1% to about 30%, from about 1% to about 20%, orfrom about 2% to about 12%. In some embodiments, the molar ratio ofalcohol functional groups to ester functional groups in the starchcomposition is at least about 1:1, or at least about 4:1. In someembodiments, the molar ratio of alcohol functional groups to esterfunctional groups in the starch composition is from about 1:1 to about200:1, or from about 1:1 to about 50:1.

In some embodiments, combinations of acid and triglyceride are employedin the starch compositions. In some embodiments, the total amounts ofacid and triglyceride is from about 0.1% to about 32%, from about 1% toabout 25%, or from about 2% to about 20%. Additionally, oralternatively, the molar ratio of the alcohol functional groups to thetotal of ester and acid functional groups is at least about 1:1, or atleast about 4:1. In some embodiments, the molar is from about 1:1 toabout 200:1, or from about 1:1 to about 50:1.

Additional Components

The compositions according to the present invention may include one ormore additional components as desired for the processing and/or end useof the fibers and or plastic articles. Additional components may bepresent in any suitable amount. In some embodiments, additionalcomponents may be present in an amount of from about 0.01% to about 35%or from about 2% to about 20%. Non-limiting examples of additionalcomponents include, but are not limited to, additional polymers,processing aids and the like.

Non-limiting examples of additional polymers of use include:polyhydroxyalkanoates, polyvinyl alcohol, polyethylene, polypropylene,polyethylene terephthalate, maleated polyethylene, maleatedpolypropylene, polylactic acid, modified polypropylene, nylon,caprolactone, and combinations thereof.

In embodiments in which properties including, but not limited to,biodegradability and/or flushability are desired, additional suitablebiodegradable polymers and combinations of thereof are of use. In someembodiments, polyesters containing aliphatic components are suitablebiodegradable thermoplastic polymers. In some embodiments, among thepolyesters, ester polycondensates containing aliphatic constituents andpoly(hydroxycarboxylic) acid are preferred. The ester polycondensatesinclude, but are not limited to: diacids/diol aliphatic polyesters suchas polybutylene succinate, and polybutylene succinate co-adipate;aliphatic/aromatic polyesters such as terpolymers made of butylenesdiol, adipic acid, and terephtalic acid. The poly(hydroxycarboxylic)acids include, but are not limited to: lactic acid based homopolymersand copolymers; polyhydroxybutyrate; and other polyhydroxyalkanoatehomopolymers and copolymers. In some embodiments, a homopolymer orcopolymer of poly lactic acid is preferred. Modified polylactic acid anddifferent stereo configurations thereof may also be used. Suitablepolylactic acids typically have a molecular weight range of from about4,000 g/mol to about 400,000 g/mol. Examples of suitable commerciallyavailable poly lactic acids include NATUREWORKS™ from Cargill Dow andLACEA™ from Mitsui Chemical. An example of a suitable commerciallyavailable diacid/diol aliphatic polyester is the polybutylenesuccinate/adipate copolymers sold as BIONOLLE™ 1000 and BIONOLLE™ 3000from the Showa Highpolymer Company, Ltd. Located in Tokyo, Japan. Anexample of a suitable commercially available aliphatic/aromaticcopolyester is the poly(tetramethylene adipate-co-terephthalate) sold asEASTAR BIO™ Copolyester from Eastman Chemical or ECOFLEX™ from BASF. Insome embodiments, the biodegradable polymer or combination of polymersmay comprise polyvinyl alcohol.

The aforementioned biodegradable polymers and combinations thereof arepresent in an amount will be from about 0.1% to about 70%%, from about1% to about 50%, or from about 2% to about 25%, by weight of the presentstarch and thermoplastic starch compositions.

Processing aids are generally present in the current compositions inamounts of from about 0.1% to about 3%, or from about 0.2% to about 2%.Non-limiting examples of processing aids include: lubricants, anti-tack,polymers, surfactants, oils, slip agents, and combinations thereof.Non-limiting examples of specific processing aids include: Magnesiumstearate; fatty acid amides; metal salts of fatty acids; wax acid estersand their soaps; montan wax acids, esters and their soaps; polyolefinwaxes; non polar polyolefin waxes; natural and synthetic paraffin waxes;fluoro polymers; talc; silicon; clay; diatomaceous earth. Commercialexamples of such compounds include, but are not limited to: Crodamide™(Croda, North Humberside, UK), Atmer™ (Uniqema, Everberg, Belgium,) andEpostan™ (Nippon Shokobai, Tokyo, JP).

In some embodiments, the starch comprises at least about 50% of allpolymer components in the starch compositions, more specifically atleast about 60% of all polymer components in the starch compositions.

Water Stability

Without wishing to be bound by theory, the thermoplastic polymercompositions according to the present invention may be rendered waterstable via the aforementioned ester transesterification reaction and/orester condensation reaction. When the thermoplastic polymer compositionsare made into fibers and/or articles comprising fibers, the reactionsmay be induced before formation of the fiber and/or article, duringformation of the fiber and/or article, after the fiber's and/orarticle's formation (i.e., curing) and combinations thereof. In someembodiments, the reaction(s) are induced, and/or driven towardscompletion through the application of heat. In some embodiments of thepresent invention, a catalyst may be used to initiate and/or acceleratethe transesterification and/or ester condensation reactions. Anysuitable catalyst is of use. Non-limiting examples of useful catalystsinclude Lewis acids. A non-limiting example of a Lewis acid ispara-toluene sulfonic acid.

With regard to the ester condensation reaction, it is believed withoutbeing bound by theory that the heating of the thermoplastic polymercomposition comprising acid, may remove a sufficient amount of waterfrom the starch composition, (including some, but not all of the boundwater) to allow a reaction of the polyhydric alcohol and the acid toform a water stable reaction product to an extent that provides theresulting composition with water stability. While again not wishing tobe bound by theory, it is believed that a condensation reaction mayoccur between the polyhydric alcohol and acid. Generally, the chemistrywhich governs such condensation reactions is known in the art as alkydchemistry.

In the present invention, it may be important that the estercondensation reaction is not completed to such an extent that a gel ofthe reaction products is formed before final processing of thethermoplastic composition occurs. As used herein “gel” means a materialthat is crosslinked to an extent that flow even under high temperaturesis no longer possible without degradation of the material's molecularweight. It is important for the system to be below the gel point of thereactants before final processing so as to retain sufficient flowbehavior to enable shaping the material into films fibers or articles.The gel point is defined as the state at which enough polymer chainsformed by the products of the reactants are bonded together such that atleast one very large molecule is coextensive with the polymer phase andflow is no longer possible and the material behaves more like a solid.

Up until to the gel point, it may be advantageous for the reaction toproceed to a point where prepolymers such as oligomers or even largermolecules are formed, yet these species should retain the ability toflow and be shaped into useful articles. Oligomers as used herein arereaction products from constituent monomers that include at least twomonomers up to about ten monomers. In some embodiments of the currentinvention, when carrying out the ester condensation reaction between theacid and alcohol and thereby forming oligomers, it may be advantageousto remove excess water from the reaction product before forming the endproduct. It is believed that removal of the water will speed the estercondensation reaction toward completion in the final processing step.

In some embodiments, the thermoplastic composition is heated at atemperature of at least about 90° C., more specifically at least about100° C., to convert the thermoplastic composition to a water stablecomposition. Typically, the thermoplastic composition will not be heatedat a temperature over about 250° C., or over about 225° C. In someembodiments, the thermoplastic composition is heated at a temperature ofat least about 115° C. to convert the thermoplastic composition to awater stable composition. In further embodiments, the thermoplasticcomposition is heated at a temperature of from about 130° C. to about180° C. to convert the thermoplastic composition to a water stablecomposition. In some embodiments, the water content of the compositionis reduced to a level below the level of bound water naturally presentin the starch at ambient conditions. In other embodiments, the watercontent of the composition is reduced to 5% or less of the composition.In other embodiments, water content is about 4% or less. In anotherembodiment the water content is reduced to about 3% or less. In yetanother embodiment, the water content is reduced to about 2% or less.Water content can be reduced by providing the starch composition atelevated temperatures under conditions wherein water can vaporize.

Although not required, the physical form of the thermoplastic polymercomposition may be modified to provide a greater surface area tofacilitate water removal from the compositions. The heating timenecessary to convert a thermoplastic composition to a water stable formwill depend, in general, on a variety of factors, including componentcompositions (i.e., particular starch, polyhydric alcohol andtriglyceride and/or acid), heating temperature, physical form of thecomposition, and the like. Suitable times may range from instantaneouslyto about 24 hours, about 1 minute to about 24 hours, from about 5minutes to about 12 hours, or from about 5 minutes to about 1 hour. Ingeneral, water content should not be reduced under conditions whereindecomposition, burning or scorching of the starch occurs, particularlyin the case that visually noticeable or significant levels ofdecomposition, burning or scorching occurs.

In some embodiments, the thermoplastic compositions according to thepresent invention are formed by melt mixing and/or extruding a mixturecomprising destructured starch, polyhydric alcohol, and triglycerideand/or acid, using conventional mixing and/or extrusion techniques. Themixture may be formed by combining destructured starch, polyhydricalcohol, and triglyceride and/or acid. Alternatively, the mixture may beprovided by combining non-destructured starch, polyhydric alcohol, andtriglyceride and/or acid, with the additional step of destructuring thestarch in situ in the mixture, by any of the destructuring techniquesdiscussed above. The components are typically mixed using conventionalcompounding techniques. The objective of the compounding step is toproduce at least a visually homogeneous melt composition comprising thestarch.

A suitable mixing device is a multiple mixing zone twin screw extruderwith multiple injection points. The multiple injection points can beused to add the destructured starch, polyhydric alcohol and triglycerideand/or acid. A twin screw batch mixer or a single screw extrusion systemcan also be used. As long as sufficient mixing and heating occurs, theparticular equipment used is not critical. An alternative method forcompounding the materials comprises adding the starch, polyhydricalcohol, and triglyceride and/or acid to an extrusion system where theyare mixed in progressively increasing temperatures. For example, a twinscrew extruder with six heating zones may be employed. This procedurecan result in minimal thermal degradation of the starch and may ensurethat the starch is fully destructured. However, it may not be necessaryto extrude a melt mixture, and, in general, any method known in the artor suitable for the purposes hereof can be used to combine theingredients of the components to form the thermoplastic compositions ofthe present invention. Typically such techniques will include heat andmixing, and optionally pressure. The particular order or mixing,temperatures, mixing speeds or time, and equipment can be varied, aswill be understood by those skilled in the art, however temperatureshould be controlled such that the starch does not significantlydegrade. Further, if the temperature of the melt mixing and/or extrusionprocess is sufficiently high and for a sufficient time to eliminate atleast a portion of bound water from the starch and drive a reactionbetween the polyhydric alcohol and the acid, the thermoplasticcomposition which is formed by melt extruding these components willconvert to a water stable composition. For example, the melt extrusioncan be conducted in an extruder provided with vents or othermodifications which facilitate water removal and the conversion to awater stable composition. In such an embodiment, it is thereforeadvantageous to melt extrude the composition to a form which is suitablefor and end use including, but not limited to, fibers or nonwovenscomprising the fibers.

On the other hand, if the temperature or conditions at which the meltextrusion of the mixture comprising destructured starch, polyhydricalcohol, triglyceride and/or acid is conducted at a sufficiently lowtemperature and/or for an insufficient time to eliminate at least aportion of bound water from the starch and drive reaction between thepolyhydric alcohol, triglyceride and/or acid, the resulting extrudatecomprises thermoplastic compositions of the invention, which may befurther processed, if desired, and which are convertible to water stablecompositions by further heating. The extrudate can therefore be providedin this embodiment in a form which facilitates handling, furtherprocessing, or the like. For example, a thermoplastic compositionextrudate can be in pellet form, powder or crumb form or the like. In aspecific embodiment, the thermoplastic composition extrudate is in apellet form which is then suitable for melt extruding to a desired enduse form. In this embodiment, the further melt extrusion of pellets (orextrudate of another form) to form fibers, or articles comprisingfibers, may be conducted under sufficient conditions of temperature andtime to effect the conversion of the thermoplastic composition to awater stable composition or article. Alternatively, if the meltextrusion is not conducted under sufficient conditions of temperatureand time to effect the conversion of the thermoplastic composition to awater stable composition, the resulting extrudate may be heated furtherto effect the conversion of the extruded thermoplastic composition to awater stable article.

In some embodiments, a thermoplastic composition in the form of pelletsis formed by melt extruding destructured starch, polyhydric alcohol andtriglyceride and/or acid. The extrusion process may not providesufficient heating of the thermoplastic composition for a sufficienttime to effect conversion to a water stable composition. The pellets aresubsequently subjected to melt extrusion by conventional fiber spinningprocesses. The resulting fibers are rendered water stable by anadditional heating step at a temperature of from about 100° C., morespecifically 115° C., still more specifically from about 130° C., toabout 180° C. Alternatively, the melt spinning process is conducted at atemperature in this range under conditions by which the resulting fibersare rendered water stable. In a further embodiment, the necessary wateris eliminated from the fibers by flash evaporation as the fibers exitthe spinneret swing to the reduction in pressure.

In some embodiments, it may be advantageous to provide the polyhydricalcohol and the triglyceride and/or acid as what is termed herein as a“pre-polymer”. In these instances, the aforementionedtransesterification reaction and/or ester condensation reaction hasalready at least partially, but not completely, taken place between thepolyhydric alcohol and the triglyceride and/or acid before it is mixedwith the starch. In further embodiments, the pre-polymer may alsocontain starch. Pre-polymers may take any suitable form which may beconvenient to make, ship process and combinations thereof. Non-limitingexamples of forms include strands, pellets, powder, and combinationsthereof.

In some embodiments, a thermoplastic composition in the form of pelletsis formed by melt extruding destructured starch, polyhydric alcohol andtriglyceride and/or acid. The extrusion process does not providesufficient heating of the thermoplastic composition for a sufficienttime to effect conversion to a water stable composition. The pellets aresubsequently subjected to melt extrusion by conventional fiber spinningprocesses. The resulting fibers are rendered water stable by anadditional heating step at a temperature of from about 100° C., morespecifically 115° C., still more specifically from about 130° C., toabout 180° C. Alternatively, the melt spinning process is conducted at atemperature in this range under conditions by which the resulting fibersare rendered water stable. In a further embodiment, the necessary wateris eliminated from the fibers by flash evaporation as the fibers exitthe spinneret swing to the reduction in pressure.

In general, high fiber spinning rates are desired. Fiber spinning speedsof about 10 meters/minute or greater can be used. In some embodimentshereof, the fiber spinning speed is from about 100 to about 7,000meters/minute, or from about 300 to about 3,000 meters/minute, or fromabout 500 to about 2,000 meters/minute. The spun fibers can be collectedusing conventional godet winding systems or through air drag attenuationdevices. If the godet system is used, the fibers can be further orientedthrough post extrusion drawing as desired. The drawn fibers may then becrimped and/or cut to form non-continuous fibers (staple fibers) used ina carding, airlaid, or fluid laid process. The fiber may be made byfiber spinning processes using a high draw down ratio. The draw downratio is defined as the ratio of the fiber at its maximum diameter(which is typically occurs immediately after exiting the capillary ofthe spinneret in a conventional spinning process) to the final diameterof the formed fiber. The fiber draw down ratio via either staple,spunbond, or meltblown process will typically be 1.5 or greater, and canbe about 5 or greater, about 10 or greater, or about 12 or greater.Continuous fibers can be produced through, for example, spunbond methodsor meltblowing processes. Alternately, non-continuous (staple fibers)fibers can be produced according to conventional staple fiber processesas are well known in the art. The various methods of fiber manufacturingcan also be combined to produce a combination technique, as will beunderstood by those skilled in the art. Additionally, hollow core fibersas disclosed in U.S. Pat. No. 6,368,990 can be formed.

Typically, the diameter of fibers produced according to the presentinvention is less than about 200 microns, and in alternate embodimentsis less than about 100 microns, less than about 50 microns, or less thanabout 30 microns. In one embodiment, the fibers have a diameter of fromabout 0.1 microns to about 25 microns. In another embodiment the fibersmay have a diameter from about 0.2 microns to about 15 microns. In otherembodiment, the fibers may have a diameter from about 5 microns to about14 microns. Fiber diameter is controlled by factors well known in thefiber spinning art including, for example, spinning speed and massthrough-put.

Fibers according to the present invention include, but are not limitedto, monocomponent fibers, multicomponent fibers (such as bicomponentfibers), or biconstituent fibers. The fibers may take any suitable shapeincluding, round or non-round. Non-round fibers include, but are notlimited to those described above.

In some embodiments, the fiber is a multicomponent fiber having a sheathand a core. Either the core or the sheath or both the core and sheathmay comprise a thermoplastic starch composition according to the presentinvention. In embodiments, in which the core is a thermoplasticcomposition according to the present invention, the sheath comprises adifferent polymer. Non-limiting examples of such polymers include thoseselected from the group consisting of: polyethylene terephthalate;polyethylene; polypropylene; polyhydroxyalkanoate; polylactic acid;polyester; and combinations thereof. In embodiments in which the fiberis a multicomponent fiber having an islands-in-the-sea configuration,wherein either the islands, the sea or both comprise a thermoplasticstarch composition according to the present invention. In embodiments,in which the islands are a thermoplastic composition according to thepresent invention, the sea comprises a different polymer. Non-limitingexamples of such polymers include those selected from the groupconsisting of: polyethylene terephthalate; polyethylene; polypropylene;polyhydroxyalkanoate; polylactic acid; polyester; and combinationsthereof.

The fibers according to the present invention may be used for anypurposes for which fibers are conventionally used. This includes,without limitation, incorporation into nonwoven webs and substrates. Thefibers hereof may be converted to nonwovens by any suitable methodsknown in the art. Continuous fibers can be formed into a web usingindustry standard spunbond type technologies while staple fibers can beformed into a web using industry standard carding, airlaid, or wetlaidtechnologies. Typical bonding methods include: calendar (pressure andheat), thru-air heat, mechanical entanglement, hydrodynamicentanglement, needle punching, and chemical bonding and/or resinbonding. The calendar, thru-air heat, and chemical bonding are thepreferred bonding methods for the starch and polymer multicomponentfibers. Thermally bondable fibers are required for the pressurized heatand thru-air heat bonding methods.

The fibers of the present invention may also be bonded or combined withother synthetic or natural fibers to make nonwoven articles. Thesynthetic or natural fibers may be blended together in the formingprocess or used in discrete layers. Suitable synthetic fibers includefibers made from polypropylene, polyethylene, polyester, polyacrylates,and copolymers thereof and mixtures thereof. Natural fibers includecellulosic fibers and derivatives thereof. Suitable cellulosic fibersinclude those derived from any tree or vegetation, including hardwoodfibers, softwood fibers, hemp, and cotton. Also included are fibers madefrom processed natural cellulosic resources such as rayon.

The fibers described herein are typically used to make disposablenonwoven materials for use in articles which may find applications inone of many different uses. Specific articles of the present inventioninclude disposable nonwovens for hygiene and medical applications, morespecifically, for example, in applications such as diapers, wipes,feminine hygiene articles, drapes, gowns, sheeting, bandages and thelike. In diapers, nonwoven materials are often employed in the top sheetor back sheet, and in feminine pads or products, nonwoven materials areoften employed in the top sheet. Nonwoven articles generally containgreater than about 15% of a plurality of fibers that are continuous ornon-continuous and physically and/or chemically attached to one another.The nonwoven may be combined with additional nonwovens or films toproduce a layered article used either by itself or as a component in acomplex combination of other materials. Nonwoven articles produced fromfibers can also exhibit desirable mechanical properties, particularly,strength, flexibility and softness. Measures of strength include dryand/or wet tensile strength. Flexibility is related to stiffness and canattribute to softness. Softness is generally described as aphysiologically perceived attribute which is related to both flexibilityand texture. One skilled in the art will appreciate that the fibersaccording to the invention are also suitable for use in applicationsother than nonwoven articles.

Notwithstanding the water stability of the fibers and other articlesproduced in the present invention, the articles may be environmentallydegradable depending upon the amount of starch that is present, anyadditional polymer used, and the specific configuration of the article.“Environmentally degradable” is defined as being biodegradable,disintegratable, dispersible, flushable, or compostable or a combinationthereof. In the present invention, the fibers, nonwoven webs, andarticles may be environmentally degradable.

A specific embodiment of a method according to the invention isdescribed. A starch is destructured by ethoxylation, and a polyhydricalcohol, such as glycerol, is added to the destructured starch. A liquidpolyhydric alcohol such as glycerol can be combined with destructuredstarch via a volumetric displacement pump. The starch and polyhydricalcohol mixture is added to a mixer and typically heated to at least100° C. over a period of from about 1 to 5 minutes at about 60 rpm. Acidis added to the mixer, with continued heating over a period of fromabout 1 to about 15 minutes at about 60 rpm. Alternatively, multiplefeed zones can be used for introducing starch, polyhydric alcohol, andacid, or premixtures thereof, directly to an extruder. The resultingmixture of starch, polyhydric alcohol and acid is extruded as a rod andchopped into pellets using any suitable cutting device including, butnot limited to, a knife. After from about 18 to about 36 hours, thepellets are placed in an extruder. The extruder barrel is preheated toat temperature of about 100° C. to about 200° C. Fibers are extruded bymelt spinning at a temperature sufficient to flash off residual waterand render the fibers water stable.

The starch-containing compositions and process of the present inventioncan also be used to make forms other than fibers, such as, but notlimited to, films and molded articles using conventional techniquesknown in the art.

EXAMPLES

The examples below further illustrate the present invention.

Example 1

This example demonstrates melt mixing and one-shot spinning of waterstable fibers. The following materials are mixed in a Haake Rheocord 90melt mixer, Thermo Electron Corporation, Newington, N.H.:

-   30 g Ethylex™ 2015 hydroxyethylated starch (Tate & Lyle, Decatur,    Ill.)-   12.5 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)-   7.5 g Soybean oil (Aldrich Chemicals, St. Louis, Mo.)-   0.0125 g p-Toluenesulfonic acid (Aldrich Chemicals, St. Louis, Mo.)

The starch and the glycerol are mixed for about 3 minutes at about 60rpm at a temperature of about 160° C. The balance of components areadded and mixed for an additional 7 minutes at about 60 rpm. Thecontents are removed and allowed to cool to room temperature. Themixture is then chopped using a knife into pieces approximately 50 mm indiameter.

After 24 hours, the pieces are placed into a piston/cylinder one shotspinning system, Alex James, Inc. of Greer, S.C. The extruder barrel ispreheated to 160° C. The spinneret capillary is 0.016″ diameter and hasan L/D of 3. Fibers are extruded by activating the piston at anextrusion rate of approximately 0.8 g/minute. Approximately 50 g offibers are collected.

Approximately 20 g of the fibers are dried in a vacuum oven at 90° C.and 30 mm Hg for 12 hours. Another 20 g of the fibers are dried in aconvection oven at 115° C. for 12 hours. The remaining 10 g of fibersare simply allowed to cool for 12 hours at ambient air temperature(about 22° C.). The respective fibers are subjected to the waterstability test as described herein. The fibers which are dried atelevated temperature (90° C. and 115° C.) do not dissolve or break-up,displaying water stability as defined herein. Fibers that are allowedsimply to cool, without heat treatment, break up completely after 1 hourin water.

Comparative Example 2

This example demonstrates a conventional process for melt mixing andone-shot spinning of starch fibers which are not water stable. Thefollowing materials are mixed in the described Haake Rheocord 90 meltmixer:

-   30 g Ethylex™ 2015 starch (Tate & Lyle, Decatur, Ill.)-   12.5 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)

The starch and the glycerol are mixed for about 10 minutes at about 60rpm at a temperature of about 160° C. The contents are removed andallowed to cool to room temperature. The mixture is then chopped using aknife into pieces approximately 50 mm in diameter. After 24 hours, thepieces are placed into the described piston/cylinder one shot spinningsystem. The extruder barrel is preheated to 160° C. The spinneretcapillary is 0.016″ diameter and has an L/D of 3. Fibers are extruded byactivating the piston at an extrusion rate of approximately 0.8g/minute. Approximately 40 g of fibers are collected.

Approximately 10 g of the fibers are dried in a vacuum oven at 90° C.and 30 mm Hg for 12 hours. Another 10 g of the fibers are dried in aconvection oven at 115° C. for 12 hours. The remaining 10 g of fibersare simply allowed to cool for 12 hours at ambient air temperature(about 22° C.). The fibers are subjected to the described waterstability test. In this case, the fibers that are dried at elevatedtemperature (90° C. and 115° C.) and those that are allowed to cool toambient temperature all break up completely after 1 hour in water.

Example 3

This example demonstrates melt mixing and one-shot spinning of waterstable starch fibers of various compositions. The following materialsare mixed in the described Haake Rheocord 90 melt mixer in a manner asdescribed in Example 1 and melt blended. Approximately 50 g of eachcomposition is made. Ethylex ™ Glycerol Linseed oil Soybean oilp-Toluenesulfonic 2015 starch (Aldrich (Aldrich (Aldrich acid (AldrichMaterial, (Tate& Lyle, Chemicals, Chemicals, Chemicals, Chemicals, wt %Decatur, IL) St. Louis, MO) St. Louis, MO) St. Louis, MO) St. Louis, MO)Sample 1 60 25 12.5 2.4 0.1 Sample 2 60 25 10 4.9 0.1 Sample 3 60 25 7.57.4 0.1

After 24 hours, the materials are spun into fibers using the describedpiston/cylinder one shot spinning system. The extruder barrel ispreheated to 160° C. The spinneret capillary is 0.016″ diameter and hasan L/D of 3. Fibers are extruded by activating the piston at anextrusion rate of approximately 0.8 g/minute. Approximately 40 g offibers of each composition are collected.

Approximately 20 g of each composition of fibers are dried in aconvection oven at 115° C. for 12 hours, and about 10 g of eachcomposition of fibers are simply allowed to cool for 12 hours at ambientair temperature (about 22° C.). The fibers are subjected to thedescribed water stability test, with the following results: Result ofwater Result of water stability test for stability test for heat treatedfibers untreated fibers Material (2 weeks) (2 weeks) Sample 1 Pass FailSample 2 Pass Fail Sample 3 Pass Fail

Example 4

This example demonstrates additional blending and spinning of fiberswith water stability. The following materials are used:

-   3500 g Ethylex™ 2015 (Tate & Lyle, Decatur, Ill.)-   1095 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)-   438 g Linseed oil (Aldrich Chemicals, St. Louis, Mo.)-   438 g Stearic acid (Aldrich Chemicals, St. Louis, Mo.)-   50 g Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)

The starch, linseed oil, stearic acid and magnesium stearate (employedas a process aid) are dry mixed in a Henschel Raw Material Mixer (GreenBay, Wis.) for 4 minutes at 1000 rpm. The mixture is then fed into a B&PProcess System Twin Screw Extrusion Compounding System (Saginaw, Mich.)with 40 mm co-rotating screws. Glycerol is fed through a liquid feedport at a rate that maintains the desired composition stated above. Thescrew speed is set at 90 rpm with the thermal profile as shown below:Temperature zone 1 zone 2 zone 3 zone 4 zone 5 zone 6 zone 7 zone 8 zone9 die Set (° C.) 85 85 100 145 155 160 160 160 140 100 Actual (° C.) 8383 85 138 138 144 155 147 133 98

At these conditions the overall extrusion rate is 20 lbs/hour. A vacuumline is applied to two of three vent ports to extract water from thematerial during pelletization. Torque is 10%. The mixture is extrudedinto strands 0.3-0.8 cm in diameter and the strands are chopped to formpellets via a Conair pellitizer. The pellets are dried for 12 hours in athrough air dryer at 150° F. The pellets are fed into a Hills 4-holeextruder test stand (Hills, Inc., West Melbourne, Fla.) with a Hillsbicomponent sheath/core 4-hole spin pack. The equipment features twoextruders that feed to a single spin head to produce bicomponent fibers.For single component fibers, both extruders are set to identicalconditions as follows and the same material is fed into both extruders:Extruder Melt Barrel Barrel Barrel Extruder Melt Pump Spin Pressure Zone1 Zone 2 Zone 3 Pressure Speed Head (psi) (° C.) (° C.) (° C.) (psi)(rpm) (° C.) Set Extruder 1 1400 160 160 160 1500 464 165 Set Extruder 21400 160 160 160 1500 464

Fibers are collected in free fall at a mass throughput of 0.8g/hole-min. The fibers are collected and dried overnight in a convectionoven at 115° C. The fibers are subjected to the water stability test.All fibers pass the water stability test.

Example 5

This example demonstrates blending and spinning of bicomponent fiberswith water stability. The following materials are used to produce athermoplastic composition:

-   3500 g Ethylex™ 2015 (Tate & Lyle, Decatur, Ill.)-   1095 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)-   438 g Soybean oil (Aldrich Chemicals, St. Louis, Mo.)-   2 g p-Toluenesulfonic acid (Aldrich Chemicals, St. Louis, Mo.)-   50 g Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)

The starch, soybean oil, p-Toluenesulfonic acid, and magnesium stearateare mixed in a Henschel Raw Material Mixer (Green Bay, Wis.) for 4minutes at 1000 rpm. The mixture is then fed into the described B&PProcess System Twin Screw Extrusion Compounding System. Glycerol is fedthrough a liquid feed port at a rate that maintains the desiredcomposition stated above. The screw speed is set at 90 rpm with thethermal profile as employed in Example 4.

The overall extrusion rate is 20 lbs/hour. A vacuum line is applied totwo of three vent ports to extract water from the material duringpelletization. Torque is 10%. The mixture is extruded into strands0.3-0.8 cm in diameter and the strands are chopped to form pellets via aConair pellitizer. The pellets are dried for 12 hours in a through airdryer at 150° F. The pellets are fed in the described Hills 4-holeextruder test stand with the bicomponent sheath/core 4-hole spin pack.For bicomponent fibers, the thermoplastic composition as described aboveis fed into extruder 1. In the second extruder a polylactic acid (PLA)obtained from Natureworks LLC (Grade 6251D) is used, under the followingconditions: Extruder Melt Barrel Barrel Barrel Extruder Melt Pump SpinPressure Zone 1 Zone 2 Zone 3 Pressure Speed Head (psi) (° C.) (° C.) (°C.) (psi) (rpm) (° C.) Set Extruder 1400 180 190 190 1500 464 190 1(TPS) Set Extruder 1400 150 160 160 1500 464 2 (PLA)

This produces a 50/50 sheath/core fiber. The fibers are collected infree fall at a mass throughput of 0.8 g/hole-min. The fibers are driedovernight in a convection oven at 115° C. The fibers are subjected tothe water stability test. All fibers passed.

Example 6

Fibers Blended With PP

This example demonstrates additional blending and spinning of fiberswith water stability. The following materials are used:

-   6000 g Ethylex™ 2065 (Tate & Lyle, Decatur, Ill.)-   2500 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)-   500 g Polypropylene Profax™ PH835 (Basell, Elkton, Md.)-   500 g Maleated Polypropylene G3003 (Eastman Chemicals, Kingsport,    Tenn.)-   500 g Soybean oil (Aldrich Chemicals, St. Louis, Mo.)-   2.5 g p-Toluenesulfonic acid (Aldrich Chemicals, St. Louis, Mo.)-   50 g Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)

The components except glycerol are mixed in a Henschel Raw MaterialMixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The mixture is thenfed into a B&P Process System Twin Screw Extrusion Compounding System(Saginaw, Mich.) with 40 mm co-rotating screws. Glycerol is fed througha liquid feed port at a rate that maintains the desired composition(stated above). The screw speed is set at 90 rpm with the thermalprofile as shown below: Temperature zone 1 zone 2 zone 3 zone 4 zone 5zone 6 zone 7 zone 8 zone 9 die Set (° C.) 85 85 100 145 155 160 160 160140 100 Actual (° C.) 83 83 85 138 138 144 155 147 133 98

At these conditions the overall extrusion rate is 20 lbs/hour. A vacuumline is applied to two of three vent ports to extract water from thematerial during pelletization. Torque is 10%. The mixture is extrudedinto strands 0.3-0.8 cm in diameter and the strands are chopped to formpellets via a Conair pellitizer. The pellets are dried for 12 hours in athrough air dryer at 150° F. The pellets are fed into a Hills 4-holeextruder test stand (Hills, Inc., West Melbourne, Fla.) with a Hillsbicomponent sheath/core 4-hole spin pack. The equipment features twoextruders that feed to a single spin head to produce bicomponent fibers.For single component fibers, both extruders are set to identicalconditions as follows and the same material is fed into both extruders:Extruder Melt Barrel Barrel Barrel Extruder Melt Pump Spin Pressure Zone1 Zone 2 Zone 3 Pressure Speed Head (psi) (° C.) (° C.) (° C.) (psi)(rpm) (° C.) Set Extruder 1400 125 160 170 1500 464 175 1 (° C.) SetExtruder 1400 125 160 170 1500 464 2 (° C.)

Fibers are collected through an attenuating air jet set at 20 psi. Amass throughput of 0.75 g/hole-min is maintained. The fibers arecollected and dried overnight in a convection oven at 115° C. The fibersare subjected to the water stability test. All fibers pass the waterstability test.

Example 7

This example demonstrates blending and spinning of bicomponent fiberswith water stability. The following materials are used to produce athermoplastic composition:

-   6000 g Ethylex™ 2065 (Tate & Lyle, Decatur, Ill.)-   2500 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)-   500 g Polypropylene Profax™ PH835 (Basell, Elkton, Md.)-   500 g Maleated Polypropylene G3003 (Eastman Chemicals, Kingsport,    Tenn.)-   750 g Linseed oil (Aldrich Chemicals, St. Louis, Mo.)-   2.5 g p-Toluenesulfonic acid (Aldrich Chemicals, St. Louis, Mo.) 50    g Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)

All the components except glycerol are mixed in a Henschel Raw MaterialMixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The mixture is thenfed into a B&P Process System Twin Screw Extrusion Compounding System(Saginaw, Mich.) with 40 mm co-rotating screws. Glycerol is fed througha liquid feed port at a rate that maintains the desired composition(stated above). The screw speed is set at 90 rpm with the thermalprofile as shown below: Temperature zone 1 zone 2 zone 3 zone 4 zone 5zone 6 zone 7 zone 8 zone 9 die Set (° C.) 85 85 100 145 155 160 160 160140 100 Actual (° C.) 83 83 85 138 138 144 155 147 133 98

At these conditions the overall extrusion rate is 20 lbs/hour. A vacuumline is applied to two of three vent ports to extract water from thematerial during pelletization. Torque is 10%. The mixture is extrudedinto strands 0.3-0.8 cm in diameter and the strands are chopped to formpellets via a Conair pellitizer. The pellets are dried for 12 hours in athrough air dryer at 150° F. The pellets are fed into a Hills 4-holeextruder test stand (Hills, Inc., West Melbourne, Fla.) with a Hillsbicomponent sheath/core 4-hole spin pack. The equipment features twoextruders that feed to a single spin head to produce bicomponent fibers.For bicomponent fibers, the thermoplastic composition as described aboveis fed into extruder 1. In the second extruders a polypropylene Profax™PH835 (Basell) is used, under the following conditions: Extruder MeltBarrel Barrel Barrel Extruder Spin Pressure Zone 1 Zone 2 Zone 3Pressure Head (psi) (° C.) (° C.) (° C.) (psi) (° C.) Set Extruder 1400125 160 170 1500 175 1 (° C.) TPS Set Extruder 1400 165 170 175 1500 2(° C.) PP

Fibers are collected through an attenuating air jet set at 20 psi. Atotal mass throughput of 0.75 g/hole-min is maintained. Adjusting theratio of the melt pump speeds can produce sheath core fibers ofdifferent sheath thicknesses. The following sheath/core volume ratiosare produced: Sheath (PP) (% volume) Core (TPS) (% volume) 5 95 10 90 1585 20 80

The fibers are collected and dried overnight in a convection oven at115° C. The fibers are subjected to the water stability test. All fiberspass the water stability test.

Example 8

Bicomponent Fibers With PP

This example demonstrates blending and spinning of bicomponent fiberswith water stability. The following materials are used to produce athermoplastic composition:

-   6000 g Ethylex™ 2015 (Tate & Lyle, Decatur, Ill.)-   1900 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)-   500 g Polypropylene Profax™ PH835 (Basell, Elkton, Md.)-   500 g Maleated Polypropylene G3003 (Eastman Chemicals, Kingsport,    Tenn.)-   500 g Linseed oil (Aldrich Chemicals, St. Louis, Mo.)-   2.5 g p-Toluenesulfonic acid (Aldrich Chemicals, St. Louis, Mo.)-   50 g Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)

The components except glycerol are mixed in a Henschel Raw MaterialMixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The mixture is thenfed into a B&P Process System Twin Screw Extrusion Compounding System(Saginaw, Mich.) with 40 mm co-rotating screws. Glycerol is fed througha liquid feed port at a rate that maintains the desired composition(stated above). The screw speed is set at 90 rpm with the thermalprofile as shown below: Temperature zone 1 zone 2 zone 3 zone 4 zone 5zone 6 zone 7 zone 8 zone 9 die Set (° C.) 85 85 100 145 155 160 160 160140 100 Actual (° C.) 83 83 85 138 138 144 155 147 133 98

At these conditions the overall extrusion rate is 20 lbs/hour. A vacuumline is applied to two of three vent ports to extract water from thematerial during pelletization. Torque is 10%. The mixture is extrudedinto strands 0.3-0.8 cm in diameter and the strands are chopped to formpellets via a Conair pellitizer. The pellets are dried for 12 hours in athrough air dryer at 150° F. The pellets are fed into a Hills 4-holeextruder test stand (Hills, Inc., West Melbourne, Fla.) with a Hillsbicomponent sheath/core 4-hole spin pack. The equipment features twoextruders that feed to a single spin head to produce bicomponent fibers.For bicomponent fibers, the thermoplastic composition as described aboveis fed into extruder 1. In the second extruders a polypropylene Profax™PH835 (Basell) is used, under the following conditions: Extruder MeltBarrel Barrel Barrel Extruder Spin Pressure Zone 1 Zone 2 Zone 3Pressure Head (psi) (° C.) (° C.) (° C.) (psi) (° C.) Set Extruder 1400125 160 170 1500 175 1 (° C.) TPS Set Extruder 1400 165 170 175 1500 2(° C.) PP

Fibers are collected through an attenuating air jet set at 20 psi. Atotal mass throughput of 0.75 g/hole-min is maintained. Adjusting theratio of the melt pump speeds can produce sheath core fibers ofdifferent sheath thicknesses. The following sheath/core volume ratiosare produced: Sheath (PP) (% volume) Core (TPS) (% volume) 5 95 10 90 1585 20 80

The fibers are collected and dried overnight in a convection oven at115° C. The fibers are subjected to the water stability test. All fiberspass the water stability test.

Example 9

Binder Fibers

This example demonstrates additional blending and spinning of binderfibers with water stability. The following materials are used:

-   6000 g Ethylex™ 2015 (Tate & Lyle, Decatur, Ill.)-   2500 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)-   350 Soybean oil (Solutia Chemicals, St. Louis, Mo.)-   2 g p-Toluenesulfonic acid (Aldrich Chemicals, St. Louis, Mo.)-   500 g Maleated polypropylene (Eastman Chemicals, Kingsport, Tenn.)-   50 g Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)

All components except glycerol are mixed in a Henschel Raw MaterialMixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The mixture is thenfed into a B&P Process System Twin Screw Extrusion Compounding System(Saginaw, Mich.) with 40 mm co-rotating screws. Glycerol is fed througha liquid feed port at a rate that maintains the desired composition(stated above). The screw speed is set at 90 rpm with the thermalprofile as shown below: Temperature zone 1 zone 2 zone 3 zone 4 zone 5zone 6 zone 7 zone 8 zone 9 die Set (° C.) 85 85 100 145 155 160 160 160140 100 Actual (° C.) 83 83 85 138 138 144 155 147 133 98

At these conditions the overall extrusion rate is 20 lbs/hour. A vacuumline is applied to two of three vent ports to extract water from thematerial during pelletization. Torque is 10%. The mixture is extrudedinto strands 0.3-0.8 cm in diameter and the strands are chopped to formpellets via a Conair pellitizer. The pellets are dried for 12 hours in athrough air dryer at 150° F. The pellets are fed into a Hills 4-holeextruder test stand (Hills, Inc., West Melbourne, Fla.) with a Hillsbicomponent sheath/core 4-hole spin pack. The equipment features twoextruders that feed to a single spin head to produce bicomponent fibers.For single component fibers, both extruders are set to identicalconditions as follows and the same material is fed into both extruders:Extruder Melt Barrel Barrel Barrel Extruder Melt Pump Spin Pressure Zone1 Zone 2 Zone 3 Pressure Speed Head (psi) (° C.) (° C.) (° C.) (psi)(rpm) (° C.) Set Extruder 1400 125 160 170 1500 464 165 1 (° C.) SetExtruder 1400 125 160 170 1500 464 2 (° C.)

Fibers are collected in on a screen through an attenuating air jet at amass throughput of 0.8 g/hole-min. The air jet is set at 20 psi. TheThermoplastic starch fibers are collected, chopped with a knife tolengths approximately 2 cm. The starch fibers are mixed with unbondedstaple polyester fibers (Wellman, Fort Mill, S.C.) at a ratio of 10:1 byweight polyester to starch web for a total basis weight of approximately50 gsm. The unbonded web is placed in a Carver™ Press and pressed at1000 psi at 165° C. for 10 minutes between Teflon sheets. The web isremoved and allowed to cool. The web is dried overnight in a vacuum ovenat 115° C. The web is subjected to the following water stability test: A5 cm×5 cm web is placed in 1000 ml of water and allowed to soak for 24hours. The web is removed and if it remains intact, it is said to passthe water stability test. The dried web passes the water stability test.

Example 10

This example demonstrates blending and spinning of bicomponent fiberswith water stability. The following materials are used to produce athermoplastic composition:

-   6000 g Ethylex™ 2015 (Tate & Lyle, Decatur, Ill.)-   1900 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)-   500 g Polypropylene Profax™ PH835 (Basell, Elkton, Md.)-   500 g Maleated Polypropylene G3003 (Eastman Chemicals, Kingsport,    Tenn.)-   500 g Adipic acid (Solutia Chemicals, St. Louis, Mo.)-   500 g Linseed oil (Aldrich Chemicals, St. Louis, Mo.)-   50 g Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)

All the components except glycerol are mixed in a Henschel Raw MaterialMixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The mixture is thenfed into a B&P Process System Twin Screw Extrusion Compounding System(Saginaw, Mich.) with 40 mm co-rotating screws. Glycerol is fed througha liquid feed port at a rate that maintains the desired composition(stated above). The screw speed is set at 90 rpm with the thermalprofile as shown below: Temperature zone 1 zone 2 zone 3 zone 4 zone 5zone 6 zone 7 zone 8 zone 9 die Set (° C.) 85 85 100 145 155 160 160 160140 100 Actual (° C.) 83 83 85 138 138 144 155 147 133 98

At these conditions the overall extrusion rate is 20 lbs/hour. A vacuumline is applied to two of three vent ports to extract water from thematerial during pelletization. Torque is 10%. The mixture is extrudedinto strands 0.3-0.8 cm in diameter and the strands are chopped to formpellets via a Conair pellitizer. The pellets are dried for 12 hours in athrough air dryer at 150° F. The pellets are fed into a Hills 4-holeextruder test stand (Hills, Inc., West Melbourne, Fla.) with a Hillsbicomponent sheath/core 4-hole spin pack. The equipment features twoextruders that feed to a single spin head to produce bicomponent fibers.For bicomponent fibers, the thermoplastic composition as described aboveis fed into extruder 1. In the second extruders a polypropylene Profax™PH835 (Basell) is used, under the following conditions: Extruder MeltBarrel Barrel Barrel Extruder Spin Pressure Zone 1 Zone 2 Zone 3Pressure Head (psi) (° C.) (° C.) (° C.) (psi) (° C.) Set Extruder 1400125 160 170 1500 175 1 (° C.) TPS Set Extruder 1400 165 170 175 1500 2(° C.) PP

Fibers are collected through an attenuating air jet set at 20 psi. Atotal mass throughput of 0.75 g/hole-min is maintained. Adjusting theratio of the melt pump speeds can produce sheath core fibers ofdifferent sheath thicknesses. The following sheath/core volume ratiosare produced: Sheath (PP) (% volume) Core (TPS) (% volume) 5 95 10 90 1585 20 80

The fibers are collected and dried overnight in a convection oven at115° C. The fibers are subjected to the water stability test. All fiberspass the water stability test.

Example 11

This example demonstrates blending and spinning of bicomponent fiberswith water stability. The following materials are used to produce athermoplastic composition:

-   6000 g Ethylex™ 2005 (Tate & Lyle, Decatur, Ill.)-   1900 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)-   500 g Polypropylene Profax™ PH835 (Basell, Elkton, Md.)-   500 g Maleated Polypropylene G3003 (Eastman Chemicals, Kingsport,    Tenn.)-   500 g Adipic acid (Solutia Chemicals, St. Louis, Mo.)-   200 g Soybean oil (Aldrich Chemicals, St. Louis, Mo.)-   50 g Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)

All the components except glycerol are mixed in a Henschel Raw MaterialMixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The mixture is thenfed into a B&P Process System Twin Screw Extrusion Compounding System(Saginaw, Mich.) with 40 mm co-rotating screws. Glycerol is fed througha liquid feed port at a rate that maintains the desired composition(stated above). The screw speed is set at 90 rpm with the thermalprofile as shown below: Temperature zone 1 zone 2 zone 3 zone 4 zone 5zone 6 zone 7 zone 8 zone 9 die Set (° C.) 85 85 100 145 155 160 160 160140 100 Actual (° C.) 83 83 85 138 138 144 155 147 133 98

At these conditions the overall extrusion rate is 20 lbs/hour. A vacuumline is applied to two of three vent ports to extract water from thematerial during pelletization. Torque is 10%. The mixture is extrudedinto strands 0.3-0.8 cm in diameter and the strands are chopped to formpellets via a Conair pellitizer. The pellets are dried for 12 hours in athrough air dryer at 150° F. The pellets are fed into a Hills 4-holeextruder test stand (Hills, Inc., West Melbourne, Fla.) with a Hillsbicomponent sheath/core 4-hole spin pack. The equipment features twoextruders that feed to a single spin head to produce bicomponent fibers.For bicomponent fibers, the thermoplastic composition as described aboveis fed into extruder 1. In the second extruders a polypropylene Profax™PH835 (Basell) is used, under the following conditions: Extruder MeltBarrel Barrel Barrel Extruder Spin Pressure Zone 1 Zone 2 Zone 3Pressure Head (psi) (° C.) (° C.) (° C.) (psi) (° C.) Set Extruder 1400125 160 170 1500 175 1 (° C.) TPS Set Extruder 1400 165 170 175 1500 2(° C.) PP

Fibers are collected through an attenuating air jet set at 20 psi. Atotal mass throughput of 0.75 g/hole-min is maintained. Adjusting theratio of the melt pump speeds can produce sheath core fibers ofdifferent sheath thicknesses. The following sheath/core volume ratiosare produced: Sheath (PP) (% volume) Core (TPS) (% volume) 5 95 10 90 1585 20 80

The fibers are collected and dried overnight in a convection oven at115° C. The fibers are subjected to the water stability test. All fiberspass the water stability test.

Example 12

Web from TPS Fibers

TPS fiber prepared as in example 8 with a core sheath ratio of 95/5TPS/PP. Webs of approximately 60 grams/m² are bonded via heated calenderwith diamond shaped pattern (1 mm in width, at 2 mm intervals) at 60° C.The webs are dried in a oven at 115° C. for 12 hours. A 5 cm×5 cm pieceof the web is put into 1000 ml of tap water and stirred at 30 rpm for 24hours. The web is removed from the water dried in air for 24 hours thenmeasured. The length and width dimension changes by no more than 15% andthe web is essentially intact. The web is said to display waterstability.

Comparative Example 13

Web from Non Water Stable TPS Fibers

The following materials are used to produce a thermoplastic composition:

-   6000 g Ethylex™ 2015 (Tate & Lyle, Decatur, Ill.)-   2500 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)

The starch is fed into a B&P Process System Twin Screw ExtrusionCompounding System (Saginaw, Mich.) with 40 mm co-rotating screws.Glycerol is fed through a liquid feed port at a rate that maintains thedesired composition (stated above). The screw speed is set at 90 rpmwith the thermal profile as shown below: Temperature zone 1 zone 2 zone3 zone 4 zone 5 zone 6 zone 7 zone 8 zone 9 die Set (° C.) 85 85 100 145155 160 160 160 140 100 Actual (° C.) 83 83 85 138 138 144 155 147 13398

At these conditions the overall extrusion rate is 20 lbs/hour. A vacuumline is applied to two of three vent ports to extract water from thematerial during pelletization. Torque is 10%. The mixture is extrudedinto strands 0.3-0.8 cm in diameter and the strands are chopped to formpellets via a Conair pellitizer. The pellets are dried for 12 hours in athrough air dryer at 150° F. The pellets are fed into a Hills 4-holeextruder test stand (Hills, Inc., West Melbourne, Fla.) with a Hillsbicomponent sheath/core 4-hole spin pack. The equipment features twoextruders that feed to a single spin head to produce bicomponent fibers.For bicomponent fibers, the thermoplastic composition as described aboveis fed into extruder 1. In the second extruders a polypropylene Profax™PH835 (Basell) is used, under the following conditions: Extruder MeltBarrel Barrel Barrel Extruder Spin Pressure Zone 1 Zone 2 Zone 3Pressure Head (psi) (° C.) (° C.) (° C.) (psi) (° C.) Set Extruder 1400125 160 170 1500 175 1 (° C.) TPS Set Extruder 1400 165 170 175 1500 2(° C.) PP

Fibers are collected through an attenuating air jet set at 20 psi. Atotal mass throughput of 0.75 g/hole-min is maintained. Adjusting theratio of the melt pump speeds can produce sheath core fibers ofdifferent sheath thicknesses. The following sheath/core volume ratios isproduced: Sheath (PP) (% volume) Core (TPS) (% volume) 5 95

Webs of approximately 60 grams/m² are bonded via heated calender withdiamond shaped pattern (1 mm in width, at 2 mm intervals) at 165° C. Thewebs are dried in a oven at 115° C. for 12 hours. A 5 cm×5 cm piece ofthe web is put into 1000 ml of tap water and stirred at 30 rpm for 24hours. The web is removed from the water dried in air for 24 hours thenmeasured. The length and width dimension changes by more than 15% andthe web is not essentially intact with missing pieces. The web is saidto not display water stability.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm”.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension discloses as “40 mm” is intended to mean“about 40 mm”.

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

1. A fiber comprising a thermoplastic starch composition, saidcomposition comprising: a. destructured starch; and b.transesterification products formed from a reactant mixture comprising:i. polyhydric alcohol having alcohol functional groups; and ii.triglyceride having ester functional groups; said functional groupsbeing present in said reactant mixture in a molar ratio of said alcoholfunctional groups to said ester functional groups of from about 1:1 toabout 200:1; wherein said fiber is Water Stable.
 2. The fiber of claim1, wherein said triglyceride is present in oil selected from the groupconsisting of: coconut oil; corn germ oil; olive oil; palm seed oil;cottonseed oil; palm oil; rapeseed oil; sunflower oil; whale oil;soybean oil; peanut oil; linseed oil; tall oil; and combinationsthereof.
 3. The fiber of claim 1, said composition further comprisingester condensation reaction products formed from a reactant mixturecomprising: polyhydric alcohol and acid with at least one functionalgroup selected from the group consisting of: carboxylic acid; carboxylicacid anhydride; and combinations thereof.
 4. The fiber of claim 3,wherein said acid is selected from the group consisting of: monoacid;diacid; polyacid; polymer comprising at least one acid moiety;co-polymer comprising at least one acid moiety; anhydrides thereof; andcombinations thereof.
 5. The fiber of claim 4, wherein said acid isselected from the group consisting of: adipic acid; sebatic acid; lauricacid; stearic acid; myristic acid; palmitic acid; oleic acid; linoleicacid; sebacic acid; citric acid; oxalic acid; malonic acid; succinicacid; glutaric acid; maleic acid; fumaric acid; phthalic acid;isophthalic acid; terphthalic acid; acrylic acid; polyacrylic acid;ethylene acrylic acid copolymers; methacrylic acid; itaconic acid;glycidyl methacrylate; and combinations thereof.
 6. The fiber of claim4, wherein said acid is selected from the group consisting of: maleicacid anhydride; phthalic acid anhydride; succinic acid anhydride; andcombinations thereof.
 7. The fiber of claim 1, wherein said polyhydricalcohol is selected from the group consisting of: glycerol; glycol;sugar; sugar alcohol; and combinations thereof.
 8. The fiber of claim 1,wherein said thermoplastic composition further comprises additionalpolymer selected from the group consisting of: polyhydroxyalkanoate;polyvinyl alcohol; polyethylene; polypropylene; maleated polyethylene;maleated polypropylene; polyethylene terephthalate; polylactic acid;modified polypropylene; nylon; caprolactone; and combinations thereof.9. The fiber of claim 1, wherein said fiber is biodegradable.
 10. Thefiber of claim 9, wherein said thermoplastic composition furthercomprises additional polymer selected from the group consisting of:polyvinyl alcohol; ester polycondensates; aliphatic/aromatic polyesters;and combinations thereof.
 11. The fiber of claim 10, wherein saidpolymers are selected from the group consisting of: polybutylenesuccinate; polybutylene succinate co-adipate; co-polyesters of butylenediol, adipic acid, terephtalic acid, and combinations thereof; andcombinations thereof.
 12. The fiber of claim 1, wherein said fiber isselected from the group consisting of monocomponent fibers;multicomponent fibers; multiconstituent fibers; and combinationsthereof.
 13. The fiber of claim 12, wherein said fiber is amulticomponent fiber having a sheath and a core, said core comprisingsaid thermoplastic starch composition.
 14. The fiber of claim 13,wherein said sheath comprises polymers selected from the groupconsisting of: polyethylene terephthalate; polyethylene; polypropylene;polyhydroxyalkanoate; polylactic acid; polyester; and combinationsthereof.
 15. The fiber of claim 12, wherein said fiber is amulticomponent fiber having an islands-in-the-sea configuration, whereinsaid islands comprise said thermoplastic starch composition.
 16. Anonwoven fabric comprising the fiber of claim
 1. 17. A personal hygienearticle comprising the fiber of claim
 1. 18. An absorbent articlecomprising the fiber of claim
 1. 19. A method of making fiber comprisingthe steps of: a. forming a mixture of: i. destructured starch; ii.polyhydric alcohol having alcohol functional groups; and iii.triglyceride having ester functional groups; b. extruding said mixturethrough a spinneret at elevated temperature to form fibers; and c.inducing an transesterification reaction between at least a portion ofsaid polyhydric alcohol and said triglyceride; wherein said fiber isWater Stable.
 20. The method of claim 19, wherein saidtransesterification reaction is induced by heating said fiber to atleast about 90° C.
 21. The method of claim 19, comprising the step ofdestructuring said starch in situ.
 22. The method of claim 19, whereinsaid mixture comprises: a. from about 50% to about 85% of saiddestructured starch; b. from about 10% to about 30% of said polyhydricalcohol; and c. from about 1% to about 20% of said triglyceride.
 23. Themethod of claim 19, wherein said functional groups are present in saidmixture at a molar ratio of alcohol to ester functional groups of fromabout 1:1 to about 200:1.
 24. The method of claim 19, comprising thesteps of: a. adding acid with at least one functional group selectedfrom the group consisting of: carboxylic acid; carboxylic acidanhydride; and combinations thereof; to said mixture; and b. inducing anester condensation reaction between at least a portion of saidpolyhydric alcohol and said acid.
 25. A method of making a nonwovencomprising the steps of: a. making fibers according to the method ofclaim 19; b. laying said fibers on a fiber forming surface; and c.bonding at least a portion of said fibers together.
 26. A method ofmaking fibers comprising the steps of: a. providing a prepolymercomprising polyhydric alcohol and triglyceride wherein at least aportion of said alcohol and said triglyceride have undergone atransesterification reaction; b. mixing said prepolymer withdestructured starch; and c. extruding said mixture through a spinneretat elevated temperature to form fibers; wherein said fibers are WaterStable.
 27. The method of claim 26, comprising the step of addingadditional polyhydric alcohol.
 28. The method of claim 26, comprisingthe step of driving said transesterification reaction by heating saidfiber to at least about 90° C.
 29. The method of claim 26, comprisingthe step of degrading said starch in situ.
 30. The method of claim 26,wherein said prepolymer further comprises acid having at least onefunctional group selected from the group consisting of: carboxylic acid;carboxylic anhydride; and combinations thereof; and at least a portionof said polyhydric alcohol and said acid have undergone an estercondensation reaction.
 31. A method of making a nonwoven, comprising thesteps of: a. making fibers according to the method of claim 26; b.laying said fibers on a fiber forming surface; and c. bonding at least aportion of said fibers together.